cmd/govim: ensure go-to-def tests have stable go.mod files (#736)

golang.org/issues/36772 uncovered the fact the go-to-def tests were
making changes to go.mod files as part of the test. Whilst this
shouldn't be a problem per se, because gopls does not currently handle
cmd/go instances racing on go.mod, it makes sense to avoid this and
instead write a specific test that checks gopls behaves in the correct
way in the presence of multiple cmd/go instanes racing on go.mod.

This commit moves go-to-def tests to have stable go.mod files and
simplifies them in the process by using a module cache definition.

We also switch away from using bufname("") to the more precise
expand('%:p').

cmd/govim/testdata/scenario_default/go_to_def_module_cache.txt

@@ -9,12 +9,12 @@ vim ex 'set splitright'
 vim ex 'e '$WORK/p.go
 vim ex 'call cursor(5,18)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
+vim expr 'expand(''%:p'')'
 stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[getcurpos()[1], getcurpos()[2]]'
 stdout '^\Q[3,7]\E$'
 vim ex 'GOVIMGoToPrevDef'
-vim expr 'bufname(\"\")'
+vim expr 'expand(''%:p'')'
 stdout '^\Q"'$WORK'/p.go"\E$'
 vim expr '[getcurpos()[1], getcurpos()[2]]'
 stdout '^\Q[5,18]\E$'

cmd/govim/testdata/scenario_default/go_to_def_newtab.txt

@@ -7,10 +7,10 @@ vim ex 'set splitright'
 # Definition in unopened buffer; newtab
 vim ex 'set switchbuf=newtab'
 vim ex 'e '$WORK/p.go
-vim ex 'call cursor(5,17)'
+vim ex 'call cursor(5,20)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
-stdout '^\Q"'$WORK'/q/q.go"\E$'
+vim expr 'expand(''%:p'')'
+stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,2]\E$'
 vim expr 'string([getcurpos()[1], getcurpos()[2]])'
@@ -27,24 +27,13 @@ module mod.com/p
 
 go 1.12
 
-replace mod.com/q => ./q
-
+require example.com/blah v1.0.0
 -- p.go --
 package p
 
-import "mod.com/q"
+import "example.com/blah"
 
-const Name1 = q.Name
+const Name1 = blah.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"

cmd/govim/testdata/scenario_default/go_to_def_same_file.txt

@@ -8,7 +8,7 @@ vim ex 'set splitright'
 vim ex 'e '$WORK/p.go
 vim ex 'call cursor(6,15)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
+vim expr 'expand(''%:p'')'
 stdout '^\Q"'$WORK'/p.go"\E$'
 vim expr '[getcurpos()[1], getcurpos()[2]]'
 stdout '^\Q[8,7]\E$'
@@ -33,13 +33,3 @@ const Name1 = q.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"

cmd/govim/testdata/scenario_default/go_to_def_split.txt

@@ -7,10 +7,10 @@ vim ex 'set splitright'
 # Definition in unopened buffer; split
 vim ex 'set switchbuf=split'
 vim ex 'e '$WORK/p.go
-vim ex 'call cursor(5,17)'
+vim ex 'call cursor(5,20)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
-stdout '^\Q"'$WORK'/q/q.go"\E$'
+vim expr 'expand(''%:p'')'
+stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[2,1]\E$'
 vim expr 'string([getcurpos()[1], getcurpos()[2]])'
@@ -27,24 +27,13 @@ module mod.com/p
 
 go 1.12
 
-replace mod.com/q => ./q
-
+require example.com/blah v1.0.0
 -- p.go --
 package p
 
-import "mod.com/q"
+import "example.com/blah"
 
-const Name1 = q.Name
+const Name1 = blah.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"

cmd/govim/testdata/scenario_default/go_to_def_std_lib.txt

@@ -8,14 +8,14 @@ vim ex 'set splitright'
 vim ex 'e '$WORK/p.go
 vim ex 'call cursor(5,18)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
+vim expr 'expand(''%:p'')'
 
 # Check that we end up somewhere in GOROOT/src/time
 stdout '^\Q"'$GOROOT'/src/time/'
 
 # Now jump back and check we are where we started
 vim ex 'GOVIMGoToPrevDef'
-vim expr 'bufname(\"\")'
+vim expr 'expand(''%:p'')'
 stdout '^\Q"'$WORK'/p.go"\E$'
 vim expr '[getcurpos()[1], getcurpos()[2]]'
 stdout '^\Q[5,18]\E$'

cmd/govim/testdata/scenario_default/go_to_def_useopen.txt

@@ -4,16 +4,19 @@
 vim ex 'set splitbelow'
 vim ex 'set splitright'
 
+# Ensure the module cache is populated
+go mod download
+
 # Definition in an open window in current tab
 vim ex 'set switchbuf=useopen'
-vim ex 'e '$WORK/q/q.go
+vim ex 'e '$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,1]\E$'
 vim ex 'split '$WORK/p.go
-vim ex 'call cursor(5,17)'
+vim ex 'call cursor(5,20)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
-stdout '^\Q"'$WORK'/q/q.go"\E$'
+vim expr 'expand(''%:p'')'
+stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,1]\E$'
 vim expr 'string([getcurpos()[1], getcurpos()[2]])'
@@ -28,24 +31,13 @@ module mod.com/p
 
 go 1.12
 
-replace mod.com/q => ./q
-
+require example.com/blah v1.0.0
 -- p.go --
 package p
 
-import "mod.com/q"
+import "example.com/blah"
 
-const Name1 = q.Name
+const Name1 = blah.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"

cmd/govim/testdata/scenario_default/go_to_def_usetab.txt

@@ -4,18 +4,21 @@
 vim ex 'set splitbelow'
 vim ex 'set splitright'
 
+# Ensure the module cache is populated
+go mod download
+
 # Definition in an open window in non-current tab
 vim ex 'set switchbuf=usetab'
-vim ex 'e '$WORK/q/q.go
+vim ex 'e '$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,1]\E$'
 vim ex 'tabnew '$WORK/p.go
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,2]\E$'
-vim ex 'call cursor(5,17)'
+vim ex 'call cursor(5,20)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
-stdout '^\Q"'$WORK'/q/q.go"\E$'
+vim expr 'expand(''%:p'')'
+stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[1,1]\E$'
 vim expr 'string([getcurpos()[1], getcurpos()[2]])'
@@ -30,24 +33,13 @@ module mod.com/p
 
 go 1.12
 
-replace mod.com/q => ./q
-
+require example.com/blah v1.0.0
 -- p.go --
 package p
 
-import "mod.com/q"
+import "example.com/blah"
 
-const Name1 = q.Name
+const Name1 = blah.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"

cmd/govim/testdata/scenario_default/go_to_def_vsplit.txt

@@ -7,10 +7,10 @@ vim ex 'set splitright'
 # Definition in unopened buffer; vsplit
 vim ex 'set switchbuf=vsplit'
 vim ex 'e '$WORK/p.go
-vim ex 'call cursor(5,17)'
+vim ex 'call cursor(5,20)'
 vim ex 'GOVIMGoToDef'
-vim expr 'bufname(\"\")'
-stdout '^\Q"'$WORK'/q/q.go"\E$'
+vim expr 'expand(''%:p'')'
+stdout '^\Q"'$WORK'/.home/gopath/pkg/mod/example.com/blah@v1.0.0/main.go"\E$'
 vim expr '[winnr(), tabpagenr()]'
 stdout '^\Q[2,1]\E$'
 vim expr 'string([getcurpos()[1], getcurpos()[2]])'
@@ -27,24 +27,13 @@ module mod.com/p
 
 go 1.12
 
-replace mod.com/q => ./q
-
+require example.com/blah v1.0.0
 -- p.go --
 package p
 
-import "mod.com/q"
+import "example.com/blah"
 
-const Name1 = q.Name
+const Name1 = blah.Name
 const Name2 = SameFile
 
 const SameFile = "samefile"
-
--- q/go.mod --
-module mod.com/q
-
-go 1.12
-
--- q/q.go --
-package q
-
-const Name = "package q"